This invention relates to a method for the manufacture of a cellulase by a strain of genus Acremonium and also embraces a method for the treatment of cellulose with the cellulase so manufactured.
"Cellulase" is a generic term for a group of enzymes which hydrolyze cellulose into glucose or cellobiose and cellooligomers. In this group, there are various enzymes which are specifically called by various designations such as C.sub.1 -enzyme, C.sub.x -enzyme, and .beta.-glucosidase or exo-.beta.-glucanase, endo-.beta.-glucanase, and cellobiase, depending on the modes of action for its substrate. The true nature of these enzymes has not yet been elucidated partly because various microorganisms produce cellulase and, consequently, there occur a wide variety of enzymes exhibiting dissimilar modes of activity upon crystalline cellulose, carboxymethyl cellulose, cellodextrin, cello-oligosaccharides, cellobiose, etc. and partly because celluloses are complicated structurally. In any event, the cellulase is an enzyme complex consisting of a plurality of enzymes which exhibit a harmonized interaction so as to hydrolyze a given cellulose into components such as glucose.
In recent years, cellulase has come to attract mounting attention from the standpoint of efficient utilization of biomass resources and has consequently become a major subject of study. The cellulase produced by the strains of genus Trichoderma and genus Aspergillus which have won widespread recognition still suffer from various drawbacks such as exhibiting insufficient hydrolyzing power upon native cellulose, failing to provide complete hydrolysis of cellulose into glucose, and giving rise to large amounts of cellobiose and cello-oligosaccharides. Further, since virtually all types of cellulase heretofore known have been deficient in thermal stability, they can barely withstand protracted saccharification at temperatures on the order of 45.degree. to 50.degree. C. Thus, the reacting mixture being saccharified with such cellulase are likely to be contaminated by infectants during the course of the reaction.